Cushioning device with ventilation

ABSTRACT

An insole for a shoe is characterized by a cushioning device that circulates air between a plastic bottom layer and a soft, porous upper layer. The air is directed to designated areas of the insole via vertical apertures, which circulate air to and over the foot of a user. The bottom layer is formed with air capturing structures that when collapsed expel air that is forced through the apertures and to the surface of the user&#39;s foot. The bottom layer and the upper layer are separated by a porous middle layer that may be foam or other light weight but breathable material.

BACKGROUND

The present invention relates to foot wear, and more particularly to anovel insole for insertion into a shoe, or other cushioningapplications, that provides padding and forced ventilation using aunique multi-layer layer composition.

There is a wide variety of shoe inserts and pads on the market todaythat are intended to be placed inside a shoe for the purpose ofproviding comfort to the foot. It has long been known that shoe insertsand pads can provide a softening mechanism to absorb the shock as thefoot bears the weight of the user, and the result of this shockabsorbing function provides many orthopedic-related beneficial results.By way of example, the following references provide background into thecurrent art of shoe insert devices.

Huiskamp, U.S. Pat. No. 1,605,588, discloses a sole of a shoe with apneumatic cushion captured between a lower sole and an upper surface.The pneumatic cushion extends between the ball and the toe, and thedevice further includes perforations that compress when the wearerwalks, to pump up the sole for a softer and gentler sole.

Brahm, U.S. Pat. No. 2,474,815, discloses an air circulating insole fora shoe that vents air to the toe area by drawing in air at the heal andusing discharge valves. It has cutouts in a middle layer to locate airpassageways that travel in a longitudinal direction. Thus, air is drawnin at the back of the shoe and forced out through the front of the shoe.Air holes are placed around the toe area to give the pressurized air anescape route.

Burnham, U.S. Pat. No. 3,225,463, discloses another air ventilatedinsole, including a compressible chamber in the heel portion and anexhaust valve directed toward the toes. The chamber acts as a pump todrive air out of the valve and across the surface of the foot. Outletholes are placed around and between the toes to carry the air to the toearea before leaving the shoe.

Sandmeier, U.S. Pat. No. 4,215,492, discloses an insole for a shoe thatprovides an air flow pattern over the foot. The insole includes dimplesthat massage the foot, and have two layers that are separated by aspacer to create a gap therebetween. The upper layer has an air inletthat lets air into the gap, and as the user walks the air is forcedtoward the toe area where openings are located that vent the air. As thepressure is relieved, the air once again fills the gap in a repetitivemanner.

Sessa, U.S. Pat. No. 5,400,526, discloses a tri-layer footwear sole thathas a continuous bottom surface, and a middle layer that forms airpockets or bulb with the bottom layer. The top layer had vertical airchannels leading from the air pockets to the upper surface, where theair can contact the foot. Air is drawn into the sole at the back of theinsert by the heel, and forced upward across the foot.

Cintron, U.S. Pat. No. 5,675,914, discloses a removable footbed insertwith a single volume structure at the heel, formed in a molded lowerlayer and further including a foam upper layer. The layers haveperforations that serve as air channels, and the volume structure actsas a bellows that drives air through all three layers.

Cheng, U.S. Pat. No. 6,041,519, discloses a plurality of dome shapedstructures that are used to drive air forward to the toe area throughdesignated channels. The air is driven forward and the insert makes useof channels to direct the air to the toe area.

Ahlbäumer, U.S. Pat. No. 7,617,618, teaches an insert that has anaerating function that pumps air through the insert via an elasticallydeformable dome-shaped arch that maintains contact with the wearer'sarch for comfort. Air is driven through apertures in the insert as thedome fills with air and then is compressed by the foot.

Skaja et al., U.S. Pat. No. 7,178,267 discloses a footwear structurewhere two material layers are overlaid such that the two material layersare in contact with one another. The two material layers are heated to aforming temperature and are then vacuum-formed together to form acomposite material layer in a three-dimensional form of the footwearstructure. The sole assembly includes a first material layer made of aplastic, and a second material layer attached to the first materiallayer.

As can be seen from the foregoing, the prior art is plentiful withinserts that cushion or breathe with the action of walking. However, themechanism by which air is forced through the insert is typicallyoriginated at the heel using a large bladder or baffle, which pushes airforward along the insert using channels of some sort. This has obviousdisadvantages, including malfunction if the bellows mechanism fails andalso that the insert must be designed to accommodate this single, largeair receptacle. Further, to fill such a cavity quickly requires a ventthat can easily get clogged, rendering the entire device ineffective. Inreality, most of these bellows systems are complex and cannot distributeair throughout the insole. These devices are complex and require a greatdeal of assembly. Along with prohibitive labor costs, the complexity ofthese mechanisms also results in high defect rates in manufacturing aswell as at the consumer level. Thus there has been virtually nocommercial success with this approach. Thus, the art is in need of ashoe insert that is not reliant on a single bellows in the aft of theinsert, and will be more reliable while providing better comfort to thewearer.

SUMMARY OF THE INVENTION

A multi-layer cushioning device adapted to conform to a human body partincludes a bottom layer formed of a plastic material, the bottom layerhaving a lower surface including a plurality of uniformly spaced apartdome shaped structures (normal or inverted) extending substantially alength and a width of the lower surface. The cushioning device furthercomprises a porous middle layer on top of the bottom layer, which can begas, foam, or other shock absorbing material. A top layer is alsoprovided that has a plurality of vertical apertures that extend from thetop layer through the middle layer and down to the bottom layer,providing a multitude of airways between the top and bottom layers. In apreferred embodiment, the cushioning device also includes an upwardlyextending lateral protrusion that serves as an arch support, where theupwardly extending lateral protrusion includes column-shaped verticalrecesses on an outer surface for communicating air thereinthrough.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a side view of a first embodiment of the present invention;

FIG. 1 b is an opposite side view of the embodiment of FIG. 1 a;

FIG. 2 is a top view of the embodiment of FIG. 1 a;

FIG. 3 is a bottom view of the embodiment of FIG. 1 a;

FIG. 4 a is a cross sectional view of the embodiment of FIG. 2 takenalong lines 4 a-4 a; and

FIG. 4 b is a cross sectional view of the embodiment of FIG. 2 takenalong lines 4 b-4 b.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention is shown in FIGS. 1-4. Aninsert 10 is characterized by a cushioning device that circulates airbetween an bottom layer 12 and an upper layer 14. The air is directed todesignated areas of the insert 10 via apertures 16, which circulate airto and over the foot of a user. The bottom layer 12 and the upper layer14 are separated by an air layer 18, or alternatively the middle layercan be a foam or other light weight but breathable material. The insertis shaped to contour to a human foot and fit snugly inside a shoe,although other cushioning embodiments such as gloves, knee pads, and thelike could also be incorporated into the present invention. The bottomsurface 20 of the insert 10 includes a multitude of deformablegeometries, such as inverted, dome shaped elements 22 generallyuniformly spaced across the bottom surface as shown in FIG. 3. The domeshaped structures 22, which can serve as tack points to connect theadjacent layers, are designed to collapse under the pressure of a userwhen weight is applied, as when a step is taken, forcing air to escapethe dome shaped structure and circulate within the shoe and around thebottom layer. Some of this air is forced through apertures 16 thatextend vertically between the bottom layer 12 and the top layer 14 toexpel the air below the bottom of the foot. The dome shaped structures22 therefore not only cushion the foot by absorbing some of the energyfrom the downward pressure of the foot in its weight bearing capacity,but also provide a forced air stream around and vertically through theinsert at designated locations.

The insert is preferably formed with laterally extending protrusion orwing 26 that extends upward from the bottom surface 12 so as to contourto the arch of a user. The wing's upper surface is smooth, and its lowersurface 26 b is characterized by column-shaped recesses 28 that extendsubstantially the height of the wing 26. The top of the wing 26 forms anarc 32 that may vertically extend slightly above the height of the heel34. The column-shaped recesses 28 serve two purposes, namely they addrigidity to the insert 10 while providing vertically channels along theoutside of the insert for air to move from the bottom surface to the topsurface. These channels or recesses help to circulate the air inside theshoe as the user walks and compresses the dome shaped structure 22. Theperiphery of the insert 10 may include a lip 30 that extends around theinsert. The lip 30 can help position the insert 10 inside the shoe andprevent shifting of the insert, and can also form a semi-seal with theinner surface of the shoe to force more air through the verticalapertures 16 extending between the lower 12 and upper 14 surfaces.

The cross section of the insert 10 is shown in FIGS. 4 a and 4 b,showing the top surface and bottom surface separated by an intermediatelayer preferably of air 18. In an alternate embodiment, the air layer 18is replaced with a soft, permeable foam or other lightweight breathablematerial. The dome-shaped structures 22 extend generally the length andwidth of the bottom surface and extend roughly half way between thelower surface 12 and the upper surface 18 into the foam material 18.Each dome shaped structure has an arch profile uniformly spaced fromadjacent profiles. Similarly, the vertical apertures 16 are uniformlyspaced apart (but could alternatively be irregularly spaced for variousfunctional or cosmetic objectives), and extend from the bottom surface12 to the top surface 14, providing channels by which air can pass fromthe bottom of the insert to the top of the insert. When weight isapplied to the insert, as would occur when a user takes a step, thedome-shaped structures 22 collapse under the weight of the user's foot,forcing air trapped in the cavity of the dome-shaped structure 22 to beexpelled along the bottom surface of the insert. The shape, thickness,and material properties of the domes are selected to collapse at apredetermined rate so as to control the flow of air through the insole.Some of this expelled air will flow around the insert, aided by thevertical column-shaped recesses 28 which channels air up the side of theinsert and over the foot. Air will also be forced through the verticalapertures 16, which are preferably concentrated over the ball of thefoot and under the arch, and in the area of the toes. Air passingthrough the insert via the vertical apertures cool the foot andventilate the insert, helping to prevent moisture from collecting in theshoe. When the user lifts his or her foot, the resilient dome-shapedstructures 22 immediately return to their nominal shape and condition,ready to conduct the cycle again of collapsing and reforming with eachstep to continuously cool and ventilate the shoe. In this manner, air isconstantly circulated from the top of the insert to the bottom of theinsert and vice versa, which helps to prevent moisture build up andhelps to cool the foot.

It is to be understood that other shapes could serve the function of thedome shaped structures 22, such as cones, blocks, and volumes of variousshapes and sizes, inverted or non-inverted, and still operate within thescope of the present invention. No intention is implied that anyparticular shape or configuration is limiting in any manner with respectto the descriptions or depictions in the drawings.

The insert 10 is created in such a manner that there is an airspace orfoam 18 between the upper layer 14 and the bottom layer 12. The bottomlayer is preferably fabricated from a plastic material that is formedinto a negative mold of the insert. In the case of an airspace betweenthe layers, once the plastic bottom layer is formed, and while still ina heated condition, the interfacing upper layer is heated to a formingtemperature and placed over the bottom layer. Pressure is then appliedto the composite structure so that it forms and contacts the attachmentpoints of the plastic bottom layer 12. In a preferred embodiment, anadhesive is applied to the attachment points to create an instant andpermanent bond between the plastic bottom layer and the interfacingupper layer.

To fabricate the plastic bottom layer 12, a sheet of material is loadedinto a clamping frame. The frame is closed to secure the edges of thesheet and reliably hold it during the process. The clamp frame with thesheet is placed in a highly temperature controlled oven, preferably inbetween 2 ovens for optimum heat saturation of the material. When thematerial reaches its melt point, it is then lowered over a mold witheither male or female features. As with all components of this processthere are multiple ways to accomplish each aspect of it. For instance,instead of moving the hot sheet of material, the oven can be moved andthe mold can take its place, without moving the material. Next, a vacuumis applied, pulling the material tightly to the mold surface. The moldis kept at a stable temperature at 60 degrees Celsius, which issignificantly lower than traditional melt temperatures which can be upto 180 degrees Celsius, leading to a quicker cool down period to curethe material. Fans directed at the molded part are also turned on tohasten the curing. The clamp frame then pulls the molded part off themold or the mold is lowered to accomplish the same. The molded insertbottom layer is then removed from the machine and the process repeated.This can all be completed in less than 10 seconds. For this insert, thecycle can be in the 60 second range. Multiple insoles can bethermoformed at the same time using the proper molds and clamps.

By adding a simultaneous forming operation, a foam layer 18 may be addedto the insole 10. The foam 18 (such as ethyl vinyl acetate) is heatedand then positioned over the plastic cushioning layer 12. This plasticlayer 12 is left in the female mold so that all contact points arereinforced by the mold. A top mold is lowered onto the female formingmold, thus trapping and sealing off the foam layer 18. The heated foamlayer 18 with a heat activated adhesive or hot melt is then pressed todesignated attachment points by accurately applied air pressure. At thesame time, the edge of the foam layer 18 is pressed tightly to theplastic cushioning layer. This process securely and consistentlyattaches the foam layer 18 to the bottom plastic layer 12 veryaccurately and allows manipulation of the intervening space between thelower and upper layers. This simultaneous molding of the foam layereliminates the pre-molding foam operation and equipment. It also cutsthe total process time in half, and reduces the need for precisionmatched tooling that is needed without this process.

The use of controlled air pressure to attach the 2 or more materialsallows for complex tack points to be managed. This keeps the cushioninggeometries fully functional and allows accurate control of the air spacebetween layers. It is very difficult and expensive to align pressingequipment to accomplish the same. If there is any misalignment ormaterial thickness variation at all, the result can be a defective part.

Plastic meshes can also be used as the lower layer 12. These meshes arebreathable materials that can be thermoformed into any shape byinstalling a vacuum barrier in the forming machine. This barrier ispreferably a silicone sheet which traps the mesh between itself and thevacuum, thus pulling the mesh into the mold surface. All the otherprocess remains the same. The present inventors are unaware of any otherprocess that can produce parts with the level of porosity availableusing this method. Injection molding, for example, can mold mesh, butonly on a relatively flat surface and the cost is prohibitive for anyproduct that requires multiple molds such as footwear.

The above-described process greatly reduces mold costs that are typicalfor footwear products. The low pressure molds are generally made ofaluminum, and require no match mold sets. The cost of these molds isless than half the cost of typical compression molds and 80-90% lessthan injection molds. The cycle time of this process is many timesfaster than typical compression mold cycles of footwear products so thatmultiple molds are not required to meet manufacturing objectives furtherreducing mold costs. In the case of the simultaneous foam moldingoperation, an entire set of molds and molding equipment is eliminated.

The bottom layer, because of its shape retention properties, ispreferably an elastomer with high recovery properties and very highphysical properties. Plastic or thermoplastic urethane (TPU) has acombination of properties, including process properties relative tothermoforming that work well with the above-described process andproduct, such as excellent “hot strength” and a very short “formingwindow.” These two properties are important because it allows the insoleto be demolded quickly and stretched over mold features and undercutsduring demolding. It then snaps back to the formed shape with no illeffects. This feature dramatically reduces mold costs versus injectionand can make shapes that other processes cannot make at commerciallyviable prices. The TPU material is extruded into the desired sheetdimensions. A suitable thickness for this insole is 0.5 mm, with thewidth and length relative to the thermoforming machine requirements. Thesheet can be fed into the thermoforming machine in rolls or in sheets.Other materials are suitable, such as block amids, polyesters, eva,olefin, tpo, tpe, thermoset materials, and others. Foams and layers ofmaterial can also be used in this process. TPU, however, has an optimumcombination of process and physical properties as well as a relativelylow cost. It is also over engineered for human use, so it is a safematerial to use for most applications without a great deal of testing.

There are three basic thermoforming machine types that can be used toprocess the present invention.

A) Cut Sheet Shuttle. This equipment utilizes sheets of material thathave been cut to an appropriate size. The material is then shuttledbetween the ovens and the mold. Conversely, the material can stay in oneposition and then the ovens and mold are over or under the material.This machine is more economical and simpler than other equipment. It isalso easier to control material waste with this equipment. Processflexibility is also very high. Cycle time potential, and thereforeoutput is limited, however. As with all types of thermoformingequipment, computer controlled ovens and machine movements are desirableto control product consistency and production efficiency.

Rotary Thermoforming. This equipment moves the material in a circle, asit passes through the oven(s), then to molding and to demoldingstations. It allows for more operations in a smaller space. Operationssuch as insert loading or pre-heating the material are easily done withthis equipment. Even multiple molding stations or simultaneous moldingof multiple materials can be accomplished. Due to better access and morespace, semi or even full automation is possible. Top and bottom moldsand other devices can be operated independently so that various layersand inserts can be managed in one machine in a simultaneous orsequential manner with minimal cycle time loss.

In-line Roll Fed. This equipment uses rolls of material that pass overthe ovens, then over the mold, cooling and then die cutting, while stillin a roll format. Even the waste material is automatically rolled upafter die cutting. It is then recycled back into the material. Theadvantage of this equipment is speed. Cycle times as fast as ten secondsare common. Even the material extrusion process can be integrated withthis equipment, drastically reducing the cost of raw material. Thecapital cost of this equipment is higher than other types and there ismuch more set up and process restriction.

By inserting various materials and objects, sophisticated products canbe made with one single process. Decorative or functional fabrics andmeshes can be in-molded into the insole or other products. Design andcolor detail, logos, functional elements can also be in-molded. This isdue to the relatively low pressure and quick material curing involved inthermoforming. The material being molded is not subject to highpressures that other processes require. This results in inserts that aregently fused to the melted material with only moderate pressure. Thus,the insert is not distorted or deformed. TPU in particular freezesconsistently and quickly around an insert, cleanly framing it so that itappears to be attached by a hand process.

In addition, reinforcing inserts of almost any material can be added tothe product during the thermoforming process. By using heat activatedadhesives or hotmelt adhesives, the inserts are securely attached. Insome cases, no adhesives are necessary. Complete layers of material canbe inserted for various functional and decorative objectives. Insertscan be made in a number of ways, but they are preferably made by thesame thermoforming process and equipment. This is a very efficient wayto manufacture the inserts and it tends to lower their costs because ofthe unique ability of thermoforming machines to mold very thin parts.This also optimizes over head of the forming equipment and factory. Amyriad of other types of inserts designed to enhance the finishedproduct can be added as well during the manufacturing process. Issues ofcomfort, traction, bacteria control, conductivity, design, decoration,branding, perception, temperature control, functional adjustment andmany other finishing details can be addressed via in-mold insertion.

Virtually any design or graphic can be pre or post applied to thematerials. Textures can be applied to the forming molds and or thematerials. Most plastic materials can be extruded transparently, so thatdecoration can be added to either side or both sides, yielding verydesirable decoration. Paints and transfers can be also be applied to themold prior to forming so that the plastic picks up the material. Themolds and or material can also be texturized. By applying air pressureto the top of the material as it is being thermoformed, the mold textureand detail will transfer to the material at a very high level.

Male molds can also be used to form the present invention. Male moldshave the advantage of the availability of severe undercuts in thefinished part. These are not readily available with other moldingtechniques. “Undercuts” combined with materials such as TPU, open thedoor to product features not possible previously. Cushioning elementsaligned precisely to impacts on contoured objects such as body parts canbe inexpensively made this way. Another advantage of males molds is thatan entire layer of plastic can be molded over an insert or layer. Thismakes the surface of the finished product tougher and protects theinsert.

Because the thermoforming process does not require match mold sets andbecause materials such as TPU have tremendous hot strength, shapes andparts that previously could not be demolded are easily demolded.Moreover, because the thermoforming process carries heat with thefinished part, secondary and undesirable adhesion operations can beeliminated. Adhesives that activate only when heated to specifictemperatures are well suited for attaching the layers of the presentinvention. Adhesive application is then limited to the sheets ofmaterial prior to thermoforming. This operation can be highly controlledand automated and toxic releases and direct human exposure eliminated.

Supplemental components can be attached to the thermoformed insert bysimply placing them into the forming mold and then forming the plasticsheet over them. In most cases a heat activated adhesive must first beapplied to the component to that it bonds to the plastic sheet duringforming. The same can be done in a female mold, but in this case thecomponent would not be overmolded but simply attached to the plasticsheet.

As noted above, a second material can be simultaneously molded andattached to the plastic sheet. This is a useful feature in making theplastic more comfortable and perceptually acceptable for consumers. Afoam or fabric layer is important as a skin interface. The technique ofusing pressure to attached the two materials is important in assemblinga finished product. Otherwise, a matched set of tools, and very accuratematerial dimensions are required, thus driving up the cost of thefinished product and the reject rate. This would make the finishedproduct far too expensive and not viable. This is particularly true ofmore contoured products such as helmets, protective gear and otherproducts that are contoured to fit various areas of the body.

In addition to those materials discussed above, the insole may alsoinclude a non-stretch material that acts like a moderator, such as anon-woven polyester fabric, which can better distribute the impact load.This moderator can also prevent the bottom layer from compacting aroundthe dome-shaped structures. The moderator can be added to any layer, butis located adjacent the bottom layer. The insole can also be speciallytuned or adjusted to a particular user by judicious selection of thedome shape, size, and thickness, to control pronation, weightdistribution, comfort, and other factors. Further, in addition todistributing air throughout the insole, other dispersals such asdeodorant, sanitizer, and the like can also be distributed across theinsole. This component has become beneficial in assembling the eva tothe thermoplastic domes without the domes showing through the top of theinsole.

Another material that can be used for the skin or upper layer is Chitin,a material that shares some properties with cellulose and is soft,biocompatible, can inhibit bacteria growth and is easily dyed to createcolorful patterns on the top of the insole.

Another assembly option is to form each layer of material separately,coating them with heat activated adhesives and then aligning themtogether. The assembly is then inserted into a mold and heated. Pressureis then exerted on the top layer to compress all layers together. Tackpoints can be used to attach the materials only where desired.Individual layers or the entire product can be post perforated forbreathability or perceptual objectives.

It has further been discovered that the multi-layer cushioning device ofthe present invention can be stacked or layered to increase thefunctional cushioning, particularly in other applications. Usingmultiple cushioning devices in a stacked or nested arrangement candramatically increase the overall cushioning capability, and provides alow cost alternative to other materials that are far more complex andexpensive.

We claim:
 1. A multi-layer cushioning device adapted to conform to ahuman body part comprising: a bottom layer formed of a material selectedfrom plastic and thermoset, the bottom layer having a lower surfaceincluding a plurality of uniformly spaced apart dome shaped structuresextending substantially a length and a width of the lower surface; amiddle layer on top of the bottom layer; and a top layer having aplurality of vertical apertures that extend through the middle layer andthrough the bottom layer.
 2. The multi-layer cushioning device of claim1 further comprising an upwardly extending lateral protrusion, theupwardly extending lateral protrusion comprising column-shaped verticalrecesses on an outer surface for communicating air thereinthrough. 3.The multi-layer cushioning device of claim 2 wherein an upper edge ofthe lateral protrusion is an arc.
 4. The multi-layer cushioning deviceof claim 1 wherein the middle layer comprises a foam.
 5. The multi-layercushioning device of claim 1 wherein the middle layer comprises air. 6.The multi-layer cushioning device of claim 1 wherein the bottom layer isadhered to the top layer with a thermally activated adhesive.
 7. Themulti-layer cushioning device of claim 1, wherein the dome shapedstructures are inverted.
 8. The multi-layer cushioning device of claim1, wherein the device is shaped to the contour of a human foot.
 9. Themulti-layer cushioning device of claim 1, wherein the dome shapedstructures are resilient and return to an original shape oncecompressed.
 10. The multi-layer cushioning device of claim 1 furthercomprising a lip extending around a periphery thereof.
 11. Themulti-layer cushioning device of claim 1, wherein the dome shapedstructures are selected to collapse when stepped upon, expelling airaway from the bottom layer.
 12. The multi-layer cushioning device ofclaim 1, wherein the dome shaped structures extend approximately onehalf way into the middle layer.
 13. The multi-layer cushioning device ofclaim 1, wherein the bottom layer is a plastic mesh.
 14. The multi-layercushioning device of claim 1 further including a non-stretch moderatoradjacent to the bottom layer.
 15. The multi-layer cushioning device ofclaim 1, further comprising a deodorizing material dispersed when thedome-shaped structures are compressed.
 16. The multi-layer cushioningdevice of claim 1, wherein the cushioning device can be individuallytuned by adjusting the size, shape, and thickness of the dome shapedstructures.
 17. The multi-layer cushioning device of claim 1, wherein atleast one layer includes chitin.
 18. A method for fabricating a shoeinsert comprising: fabricating a bottom layer from a plastic materialthat is formed into a negative mold of the insert; heating aninterfacing layer and placing the interfacing layer over the bottomlayer while the bottom layer is still heated from the molding operation;applying an adhesive to a plurality of attachment points to create aninstant and permanent bond between the plastic bottom layer and theinterfacing layer; and applying air pressure to the interfacing layer tobond it to the plastic bottom layer.
 19. The method for fabricating ashoe insert of claim 18, wherein the plastic bottom layer is formed byselecting a sheet of plastic material and securing the sheet into aclamping frame, and then placing the clamping frame and sheet in atemperature controlled oven until a melting point is reached, whereuponthe sheet of material is placed in a negative mold and cured.
 20. Themethod for fabricating a shoe insert of claim 19, further comprisingadding a foam layer between the bottom layer and the interfacing layercomprising: heating a foam material and then positioning the foammaterial over the plastic bottom layer; lowering the interfacing layeronto a negative mold containing the bottom layer and the foam material;pressing the interfacing layer to the bottom layer at attachment pointsto trap the foam material therebetween using air pressure; and pressingan edge of the foam material into the bottom layer while the bottomlayer is in a melted state.